ANATOMY OF THE HEART

By:Dr Mohammed Faez

The Heart

The heart is a chambered muscular organ that pumps blood received from the veins into the arteries, thereby maintaining the flow of blood through the entire circulatory system.

The Heart

• The heart is surrounded by membrane called Pericardium.

The Pericardium

• The pericardium is a fibroserous sac that encloses the heart and the roots of the great vessels.

• The pericardium lies within the middle mediastinum.

The Pericardium

The Pericardium

• Its function is to restrict excessive movements of the heart as a whole and to serve as a lubricated container in which the different parts of the heart can contract.

The Pericardium• Pericardium – a double-

walled sac around the heart composed of:

1. A superficial fibrous pericardium

2. A deep two-layer serous pericardium

a. The parietal layer lines the internal surface of the fibrous pericardium

b. The visceral layer or epicardium lines the surface of the heart

• They are separated by the fluid-filled pericardial cavity

The Pericardium

The Pericardium

The Pericardium

The Pericardium

Blood Supply• The pericardium blood

supply is from the pericardiacophrenic branches of the internal thoracic arteries.

Nerve Supply• The pericardium nerve

supply the fibrous pericardium and the parietal layer of serous pericardium are supplied by the phrenic nerve.

Heart Wall

• Epicardium – visceral layer of the serous pericardium

• Myocardium – cardiac muscle layer forming the bulk of the heart

• Fibrous skeleton of the heart – crisscrossing, interlacing layer of connective tissue

• Endocardium – endothelial layer of the inner myocardial surface

Heart Wall

• Endocardium– deepest layer of the heart– smooth lining to reduce friction of bloodflow

• Myocardium– middle layer of the heart– location of muscle fibers responsible for pumping

• Pericardium– outer protective layer– composed of :– visceral pericardium– paricardial cavity– parietal pericardium

Heart Wall

Heart Wall

The Heart

• The heart is a hollow muscular organ that is somewhat pyramid shaped and lies within the pericardium in the mediastinum .

• It is connected at its base to the great blood vessels but otherwise lies free within the pericardium.

The Heart

The HeartThe heart surfaces:• The anterior (sternocostal) surface

comprises the: right atrium, atrioventricular groove, right ventricle, a small strip of left ventricle and the auricle of the left atrium.

• The inferior (diaphragmatic) surface comprises the: right atrium, atrioventricular groove and both ventricles separated by the interventricular groove.

• The posterior surface (base) comprises the left atrium receiving the four pulmonary veins.

The Heart

The Heart Chambers

• Four chambers– Two atria (Right and Left)– Two ventricles (Right and

Left)

The Heart Chambers• Atria – Features

small, thin-walled chambers

– Functions receiving chambers for

blood returning to the heart from the circulation

push the blood into the adjacent ventricles.

The Heart Chambers

• Atria – Receive blood

from Right side Superior and

Inferior Vena Cava Coronary Sinus

(draining the myocardium)

Left side Pulmonary Veins

The Heart Chambers

• Ventricles – Features

make up most of the mass of the heart

the walls of the left ventricle are 3X thicker than those of the right

The Heart Chambers

• Ventricles – Functions

discharging chambers of the heart

propel blood to Pulmonary Trunk (right ventricle), Aorta (left ventricle)

The Right Atrium

• Receives deoxygenated blood from the inferior vena cava below and from the superior vena cava above.

• Receives the coronary sinus in its lower part.

• The upper end of the atrium projects to the left of the superior vena cava as the right auricle.

The Right Atrium

• The sulcus terminalis is a vertical groove on the outer surface of the atrium. This groove corresponds internally to the crista terminalis .

• Above the coronary sinus the interatrial septum forms the posterior wall. The depression in the septum the fossa ovalis are presents the site of the foramen ovale.

RA

The Right Ventricle

• Receives blood from the right atrium through the tricuspid valve .

• The edges of the valve cusps are attached to chordae tendineae which are, in turn, attached below to papillary muscles.

The Right Ventricle

• The wall of the right ventricle is thicker than that of the atria but not as thick as that of the left ventricle.

• The wall contains a mass of muscular bundles known as trabeculae carneae.

• The infundibulum is the smooth walled outflow tract of the right ventricle.

The Right Ventricle

• The pulmonary valve is situated at the top of the infundibulum.

• It is composed of three semilunar cusps.

• Blood flows through the valve and into the pulmonary arteries via the pulmonary trunk to be oxygenated in the lungs.

RV

The Left Atrium

• Receives oxygenated blood from four pulmonary veins which drain posteriorly.

• The cavity is smooth walled except for the atrial appendage.

• On the septal surface a depression marks the fossa ovalis.

The Left Atrium

• The mitral (bicuspid) valve guards the passage of blood from the left atrium to the left ventricle.

LA

The Left Ventricle• The wall of the left ventricle is

thicker than the right ventricle but the structure is similar.

• The thick wall is necessary to pump oxygenated blood at high pressure through the systemic circulation.

• Trabeculae carneae project from the wall with papillary muscles attached to the mitral valve cusp edges by way of chordae tendineae.

The Left Ventricle

• The vestibule is a smooth walled part of the left ventricle which is located below the aortic valve .

LV

The Heart Valves• Heart valves ensure

unidirectional blood flow through the heart– Composed of an endocardium

with a connective tissue core.• Two major types– Atrioventricular valves– Semilunar valves

Atrioventricular (AV) Valves• Atrioventricular (AV) valves lie

between the atria and the ventricles– R-AV valve = tricuspid valve– L-AV valve = bicuspid or

mitral valve• AV valves prevent backflow of

blood into the atria when ventricles contract

• Chordae tendineae anchor AV valves to papillary muscles of ventricle wall– Prevent prolapse of valve

back into atrium

Atrioventricular Valve

Semilunar Heart Valves• Semilunar valves prevent backflow

of blood into the ventricles • Have no chordae tendinae

attachments• Aortic semilunar valve lies

between the left ventricle and the aorta

• Pulmonary semilunar valve lies between the right ventricle and pulmonary trunk

• Heart sounds (“lub-dup”) due to valves closing– “Lub” - closing of atrioventricular

valves– “Dub”- closing of semilunar valves

Semilunar Valve

The Heart Valves

• Right AV (Tricuspid)– separates the right

atrium from the right ventricle. Prevents backflow into atrium.

• Left AV (Bicuspid)– separates the left

atrium from the left ventricle. Prevents backflow into atrium.

• Pulmonary valve– separates the right

ventricle from the pulmonary arteries. Prevents backflow after ventricular contraction.

• Aortic valve– separates the left

ventricle from the aorta. Prevents backflow after ventricular contraction .

Atrioventricular valves Semilunar valves

The Heart Valves

Pulmonarysemilunar valve

Aorticsemilunar valve

Left AV(bicuspid)valve

Right AV(tricuspid)valve

Chordaitendineae

Papillarymuscle

The Heart Valves

Arterial Supply of the Heart

• The arterial supply of the heart is provided by the right and left coronary arteries, which arise from the ascending aorta immediately above the aortic valve.

Coronary Arteries

The origins of the coronary arteries are as follows:

• The left coronary artery arises from the aortic sinus immediately above the left posterior cusp of the aortic valve .

• The right coronary artery arises from the aortic sinus immediately above the anterior cusp of the aortic valve.

Right coronary artery

Branches– Right marginal arteries

(acute marginal artery)– Posterior

interventricular artery. (in post. IV sulcus)

– Sinoatrial nodal artery.– Atrioventricular nodal

artery.

Left coronary artery

Branches– Left anterior descending

(LAD) or anterior interventricular artery. (lies in anterior IV sulcus)• Septal branches.• Diagonal branches

– Left marginal artery. (Obtuse marginal artery)

– Left circumflex artery.

Coronary Arteries

Venous Drainage of the Heart

• Most blood from the heart wall drains into the right atrium through the coronary sinus ,which lies in the posterior part of the atrioventricular groove .

• It is a continuation of the great cardiac vein.

• It opens into the right atrium to the left of the inferior vena cava

Venous Drainage of the Heart

Nerve Supply of the Heart

• The heart is innervated by sympathetic and parasympathetic fibers of the autonomic nervous system via the cardiac plexuses situated below the arch of the aorta.

• The sympathetic supply arises from the cervical and upper thoracic portions of the sympathetic trunks, and the parasympathetic supply comes from the vagus nerves.

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External Heart: Anterior View

External Heart: Posterior View

Gross Anatomy of Heart: Frontal Section